Pinch base electric lamp with transversely arranged supply wires

ABSTRACT

A pinch-base lamp and method of making same were foils are sealed in the pinch, and secured to each foil are one end of a pole wire oriented generally parallel to the lamp axis and one end of a supply wire oriented at a right angle to the pole wire. When the lamp is mounted the laterally-extending supply wires are subjected to torsional instead of bending stress, thereby reducing the likelihood of fracturing the pinch, and the base of the pinch, being free of supply wires, may be ground to provide an accurate reference surface from the filament.

United States Patent Meijer et al.

[ Aug. 14, 1973 PINCH BASE ELECTRIC LAMP wml TRANSVERSELY ARRANGED SUPPLY WIRES Filed: May 17, 1971 Appl. No.: 144,342

Related US. Application Data Division of Ser. No. 824,478, May 14, 1969, Pat. No. 3,617,797.

Inventorsi RiksterusKugus fe Johanfies'm ria Assignee: U.S. Philips Corporation, New York,

[561 References Cited UNITED STATES PATENTS 3,548,245 12/1970 BiSCOff 65/ l 39- X 3,036,236 5/1962 Meyer 313/318 Primary Examiner-Charles W. Lanham Assistant Examiner-J. W. Davie Att0rney-Frank R. Trifari [57] ABSTRACT A pinch-base lamp and method of making same were foils are sealed in the pinch, and secured to each foil are one end of a pole wire oriented generally parallel to the lamp axis and one end of a supply wire oriented at a right angle to the pole wire. When the lamp is mounted the laterally-extending supply wires are subjected to torsional instead of bending stress, thereby reducing the likelihood of fracturing the pinch, and the base of the pinch, being free of supply wires, may be ground to provide an accurate reference surface from the filament.

2 Claims, 5 Drawing Figures l5 I4 I H 2o 2| J Li r 3 LJ '6 5 .l A 1 PINCH BASE ELECTRIC LAMP WITI-I TRANSVERSELY ARRANGED SUPPLY WIRES CROSS REFERENCE This is a division of Applicants co-pending application Ser. No. 824,478, filed May 14, 1969 now Pat. No. 3,617,797.

Known in the prior art are electric lamps having at one end a gas-tight flat pinch, and one or more metal foils sealed in the pinch; connected to each foil is the end of a current supply wire projecting outside the lamp and the end of a pole wire projecting inside the lamp space.

In these lamps it is common practice to lead the current supply wires projecting outside the lamp to the exterior through the narrow limiting of the lamp pinch remote from the lamp space. As a result of this a comparatively large space must be available for such a lamp to be mounted, for example, in a car, headlight viewed in the longitudinal direction of the said lamp. It is the object of the invention to mitigate this drawback.

According to the present invention, the lamp of the type mentioned in the preamble is characterized in that the current supply wire and the pole wire secured to the same foil .and incorporated in a pinch are arranged at right angles to each other, and the current supply wire leaves the pinch through one of the lateral narrow boundary surfaces of said pinch.

In addition to the advantage of a short length of the lamp a further advantage is obtained. When the lamp is mounted in a lamp holder which is subject to vibrations, the parts of the current supply wires emerging from the lateral narrow boundaries of said pinch are torsionally stressed in the lamp according to the invention. It has been found in practice that in the lamp according to the invention, which is comparatively short, the possibility of fracture of the pinch by the forces exerted thereon by the current supply wires in the case described, is less than when said current supply wires are stressed for bending, as is the case in the known longer lamp.

A particularly short structural length of the lamp according to the invention is obtained when it is constructed so that the current supply wires which leave a pinch through one of its narrow lateral boundaries extend outside the lamp fully laterally of the pinch.

In a further embodiment of the lamp according to the invention, the boundary of the pinch remote from the space of the envelope has a ground surface. Actually, in the lamp according to the invention, said boundary surface is free from current supply wires. Therefore the pinch can be subjected to the grinding operation at the area of said boundary surface, so that the said surface may serve as a reference surface for aligning the lamp in an associated optical system. In this manner a finished lamp can be given a prescribed light center length.

In a further embodiment of the lamp according to the invention, the current supply wires projecting from the lateral narrow boundary surfaces of the pinch consist of silicated molybdenum. As a result of this the laterally projecting wires which are exposed to the high temperatures of burner flames during the formation of the pinch, are resistent to oxidation.

An advantageous method of manufacturing a lamp according to the invention is characterized in that one or a few combinations of foils having each two wires secured thereto at right angles to each other are arranged in a jig while using a third wire to be threaded in said I jig and secured to such a foil in such manner that the first and the second of the said wires secured to such a foil extend according to and at right angles to, respectively, the longitudinal direction of the lamp to be manufactured, an envelope consisting of glass or quartz glass being then placed over said assembly after which the envelope is heated in the proximity of the foil and is squeezed in a gas-tight manner around the foils, a part of the current supply wire extending at right angles to the foil becoming located outside one of the lateral narrow boundaries of the pinch. In this method, the above mentioned third wire secured to each of the foils, only serves to fix the combinations of said foil with the two wires secured thereto at right angles to each other during the manufacture of the pinch in a jig.

The lamp according to the invention may be constructed with one or with two seals as described, in the latter case on either end of the lamp. The invention may furthermore be applied to electric filament lamps in which a filament is stretched between the pole wires or to electric discharge lamps in which the pole wires support the electrodes necessary for the discharge or serve as electrodes themselves.

In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a first embodiment of the lamp according to the invention, In this figure it is also shown in what manner a prescribed light center length can be given to such a lamp.

FIGS. 2, 3 and 4 diagrammatically show how the lamp according to the invention can be manufactured.

FIG. 5 shows a lamp in which the seal is manufactured by means of the method shown in FIGS. 2, 3 and 4.

The lamp shown in FIG. I comprises an envelope [0 consisting of quartz glass, the lower end of which is deformed to a flat pinch ll. Said pinch comprises two metal foils I2 and 13, respectively. In directions extending at right angles to each other pole wires 14 and 15, respectively, and current supply wires 16 and 17, respectively, are secured to each of the said foils. The pole wires 14 and 15 support a filament 18. The envelope 10 comprises a sealed exhaust tube 19.

As shown in the FIG. I the current supply wires 16 and 17 project from the lateral narrow'boundary surfaces 20 and 21, respectively, of the fiat pinch. As a result of this a short structural length of the lamp is ob tained.

When the current supply wires 16 and 17 are incorporated in the diagrammatically shown contacts 22 and 23 of a lamp holder (not shown), the current supply wires 16 and 17, upon vibration of the lamp holder, will mainly be torsionally stressed which, in combination with a short lamp length, results in less chance of fracture of the pinch 11 than when said current supply wires would project through the end 25 remote from the lamp space 24 of the pinch ll of a comparatively long lamp.

In the lamp according to the invention, the said end In the lamp shown the distance between the filament l8 and the end 25 of the pinch has a value a. When the light centre length prescribed for said lamp must have a value b, this requirement can be met in the lamp construction shown. This may be effected by grinding away the shaded lower portion 26 of the pinch 11 so that the end of the pinch becomes situated at 27 and the requirement regarding the light center length has been met.

A method by means of which the lamp shown in FIG. 1 can be manufactured will now be described with reference to FIGS. 2, 3 and 4.

In this method, supporting wires 43 and 44 are placed in two apertures 40 and 41, in a jig 42, which supporting wires are secured to metal foils 45 and 46. Said metal foils 45 and 46 are similar to the metal foils 12 and 13 shown in FIG. 1. In addition to the just mentioned supporting wires 43 and 44, the current supply wires 47 and 48, respectively, and the pole wires 49 and 50, respectively, are secured to said metal foils 45 and 46. A filament 51 is stretched between the pole wires 49 and 50.

A tubular envelope 52 consisting of quartz glass is then placed around said assembly, of which envelope only the lower side is shown. At its lower side said envelope comprises two slots 53 and 54, respectively, so that it can become to engage the upper side of the jig 42. The current supply wires 47 and 48 actually project through the slots 53 and 54.

As is shown particularly in FIG. 4, the jaws 55 and 56 of a pair of pincers are situated on either side of the envelope 52. These jaws have flat surfaces 57 and 58, respectively, comprising recesses 59 and 60, respectively. After the lower part of the envelope 52 has been heated to a sufficiently high temperature, for example over the region having length denoted by c, the jaws 55 and 56 of the pincers are moved towards each other and the pinch 61 of the lamp shown in FIG. 5 is formed. Due to the presence of the recesses 59 and 60 in the flat surfaces 57 and 58 of the jaws, the current supply wires 47 and 48 projecting laterally from the pinch remain free from the surfaces of the pincers. After the jaws have been moved outwards again, the product shown in FIG. 5 can be taken out of the jig. The supporting wires 43 and 44 project from the end 64 of the pinch 61 remote from the lamp space 63. These ends which do not perform any function for operating the lamp can be cut. Furthermore, if desirable, in the manner as shown in FIG. 1, the light center length of the lamp can be adjusted by grinding away the pinch 61 at its boundary surface 64.

What is claimed is:

1. A method of manufacturing an electric lamp, comprising the steps: securing to each of two foils one end of a pole wire, a current supply wire, and a support wire, the pole and support wires extending in generally parallel and opposite directions and the supply wires being transverse thereto, securing a filament to the remote ends of the pole wires, thereby forming a subassembly, disposing the remote ends of the support wires in two corresponding apertures of a jig, disposing a glass bulb over the sub-assembly to encompass same, the bulb having two slots through which the current supply wires extend, heating the bulb in the vicinity of ground end to the lamp filament. 

1. A method of manufacturing an electric lamp, comprising the steps: securing to each of two foils one end of a pole wire, a current supply wire, and a support wire, the pole and support wires extending in generally parallel and opposite directions and the supply wires being transverse thereto, securing a filament to the remote ends of the pole wires, thereby forming a subassembly, disposing the remote ends of the support wires in two corresponding apertures of a jig, disposing a glass bulb over the sub-assembly to encompass same, the bulb having two slots through which the current supply wires extend, heating the bulb in the vicinity of said sub-assembly therein, and pressing the opposite sides of the heated portion of the bulb toward each other thereby forming a pinch and sealing the foils therein.
 2. A method as defined in claim 1, comprising the further step, grinding the bottom end of the pinch, thereby removing the extending ends of the support wires and defining an accurate distance from the ground end to the lamp filament. 